Global Nitrous Oxide Production Determined by Oxygen Sensitivity of Nitrification and Denitrification

Qixing Ji, Erik Buitenhuis, Parvadha Suntharalingam, Jorge Louis Sarmiento, Bettie Ward

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

The ocean is estimated to contribute up to ~20% of global fluxes of atmospheric nitrous oxide (N 2 O), an important greenhouse gas and ozone depletion agent. Marine oxygen minimum zones contribute disproportionately to this flux. To further understand the partition of nitrification and denitrification and their environmental controls on marine N 2 O fluxes, we report new relationships between oxygen concentration and rates of N 2 O production from nitrification and denitrification directly measured with 15 N tracers in the Eastern Tropical Pacific. Highest N 2 O production rates occurred near the oxic-anoxic interface, where there is strong potential for N 2 O efflux to the atmosphere. The dominant N 2 O source in oxygen minimum zones was nitrate reduction, the rates of which were 1 to 2 orders of magnitude higher than those of ammonium oxidation. The presence of oxygen significantly inhibited the production of N 2 O from both nitrification and denitrification. These experimental data provide new constraints to a multicomponent global ocean biogeochemical model, which yielded annual oceanic N 2 O efflux of 1.7–4.4 Tg-N (median 2.8 Tg-N, 1 Tg = 10 12  g), with denitrification contributing 20% to the oceanic flux. Thus, denitrification should be viewed as a net N 2 O production pathway in the marine environment.

Original languageEnglish (US)
Pages (from-to)1790-1802
Number of pages13
JournalGlobal Biogeochemical Cycles
Volume32
Issue number12
DOIs
StatePublished - Dec 2018

All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Environmental Chemistry
  • Environmental Science(all)
  • Atmospheric Science

Keywords

  • biogeochemical model
  • marine environment
  • nitrous oxide
  • oxygen control
  • oxygen minimum zones
  • production

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